This weekend, following in the footsteps of everyone from Glenn Close and Jennifer Jason Leigh to Erika Christensen and Ali Larter, Leighton Meester will get her stalk on. The Gossip Girl is co-starring in The Roommate, a horror flick in the Single White Female mode, playing an unbalanced obsessive (who won’t stop touching other people’s stuff). It’s been a busy winter for Meester. After spending her first few years on Gossip Girl seemingly just as focused on music and fashion as on the movies, she now has her two biggest film roles to date coming out in quick succession. (Before The Roommate she was a country-singing beauty queen in January's Country Strong.) Can the one-two punch of these films help Meester establish herself as a film actress, or is her Gossip Girl persona too strong? Having said she's going to be done with Gossip Girl in two years, is she positioned to make the jump from the small to the big screen? We asked industry insiders these questions and more to answer our favorite question: If Leighton Meester were a stock, would you buy, sell, or hold?

Stock History: Meester has been working since was she 13, with recurring parts in such series as House and 24, but Gossip Girl was her first truly notable credit. Though Meester made some films during Gossip Girl's first few off seasons, up until Country Strong and The Roommate, her parts have been little more than cameos (Date Night and Going the Distance). Instead Meester has gotten attention for herself in a number of other ways: music (she signed a record deal in April 2009, sang on “Good Girls Go Bad” in June of that year, and released a single that October), fashion (like her Gossip Girl co-star Blake Lively, though not quite as Anna Wintour–approved, Meester has made herself a regular on the Fashion Week circuit, securing magazine covers and product deals while also making some boldoutfitchoices), and with her real-life, seemingly ripped-from-the-tabloids childhood (Meester's mother was in prison when she was born, such a compelling backstory she shares it with her Country Strong character).

What Hollywood Thinks: Meester has to pick her movies wisely. Says an agent, "It’s not that she's untalented, and she’s beautiful, but she’s gotta choose more carefully. The Roommate looks just ... I've actually never seen an uglier billboard. Taking that was probably a mistake. Blake Lively's just exploded after The Town and here you’ve got Leighton, with her agents stuffing her into genre schlock? It’s so competitive at the studio level. So what you gotta do is find the right indie. Something that will break at a Sundance or a Toronto. Something that gets you critical success. She’s not going to get to the next level doing these shitty movies. Mila Kunis just jumped into that level by stealing the show in Black Swan. You need to have her do something really gritty, so directors take notice. She’s not going to be in the straight offers world. But she should be working — take the fourth lead in the Baz Luhrmann movie. Or an [Alejandro González] Iñárritu movie."

Market Value: With movies like Date Night, Going the Distance, and Country Strong, Meester seemed to be eschewing the sort of trashy projects it's easier for a TV actress to land. (Tina Fey, Drew Barrymore, and Gwyneth Paltrow are classy company.) The same can't be said of The Roommate, which is exactly the kind of scary B-movie that was on Sarah Michelle Gellar and Jennifer Love Hewitt's career planners, and we all know how those worked out. Even if the movie is a box-office success, not so unlikely in a weak February frame, it won't help her make the jump in people's minds from a TV to a movie actress. Neither will Monte Carlo, which co-stars Selena Gomez, Cory Monteith, and Katie Cassidy. Nor, for that matter, does Meester's music career. It's not that Meester is untalented — as Country Strong proved, she can sing — it's just that thanks to everyone from Lindsay Lohan to Kim Kardashian, the multi-hyphenate approach seems dilettante-ish, even when it's not. It's hard to establish yourself as a serious actress, and it's hard to establish yourself as a pop star. Most people who try to do both end up doing both less well than they otherwise might. Meester does have one promising role on her docket: The Oranges, in which the much older Hugh Laurie falls for Meester, the daughter of a family friend, is an indie that could garner festival buzz,which is what Meester needs to position herself for better, higher-brow projects.

What Hollywood Thinks: Meester has to pick her movies wisely. Says an agent, "It’s not that she's untalented, and she’s beautiful, but she’s gotta choose more carefully. The Roommate looks just ... I've actually never seen an uglier billboard. Taking that was probably a mistake. Blake Lively's just exploded after The Town and here you’ve got Leighton, with her agents stuffing her into genre schlock? It’s so competitive at the studio level. So what you gotta do is find the right indie. Something that will break at a Sundance or a Toronto. Something that gets you critical success. She’s not going to get to the next level doing these shitty movies. Mila Kunis just jumped into that level by stealing the show in Black Swan. You need to have her do something really gritty, so directors take notice. She’s not going to be in the straight offers world. But she should be working — take the fourth lead in the Baz Luhrmann movie. Or an [Alejandro González] Iñárritu movie."

A manager observes that Meester's persona is still undefined: "She's made very commercial choices. What I don't know is: Who does she want to be? From looking at what she's done, it's hard to know what her plan is. Country Strong was a smart choice: Everyone in that movie was at least thought of for Oscar nominations, even if they didn't get them, if you follow me. The Oranges could be a big Sundance movie. But Monte Carlo, who knows? She sings, has an album. I think she's making better choices than just about everyone else her age on TV, but she really needs to make sure she's doing the right ones." A publicist concurs, "She's getting the right magazine covers. She was on the cover of Harper's Bazaar last fall. On the cover of Cosmo the summer before last. But what's her story? It's too early to tell."

The Analysis: It’s a recurring plot point of Gossip Girl that everything comes easily for Lively's Serena van der Woodsen. Fame, love, Yale ... Serena gets them all, effortlessly. Meanwhile, Meester's Blair Waldorf, who cares so much more about everything and schemes and plots and yearns, is constantly foiled. Nothing is effortless. This is a comparison — minus the scheming and the plotting — that one could make to the real-life actresses who play Serena and Blair. On Gossip Girl, episode in and episode out, Meester tries harder, acting circles around Lively and her décolletage. If asked to pick the more talented of the two, even a sporadic Gossip Girl watcher would pick Meester, and yet it's Lively who has successfully made herself over into a hot Hollywood commodity.

This doesn't have to be the permanent state of things, but if Meester wants to make the jump to the A-list — and the gap between TV and movie actors is bigger in Hollywood than it seems when they're rubbing up against each other in magazines — she should steal some plays from Lively's book: classy movies, not horror schlock; focus on the acting, not the music; getting Prince to serenade you is good, but rumors you're smushing with Ryan Gosling are better. A more positive takeaway from Lively: Meester, like Lively, could be just one part away from being taken seriously. But she has to get serious about finding that part.

Meester has some time. By her own count, she's got two more years until her contract on Gossip Girl ends, which gives her the steady paycheck that, theoretically, should let her avoid junk like The Roommate in the future. But if she doesn't up her status before her run on the series is over, she'll be in a challenging position: struggling to land juicy parts in films, while easily able to command leading roles in any number of new TV shows. Hey, there are worse fates than being a beloved actress with a long career, even if it is on television.

The Bottom Line: Meester has the chops, but she has to prove it to the people who don't watch Gossip Girl. Her movie selection is key here, and if she doesn't choose better fare than The Roommate going forward, we're going to get to keep her on the TV.

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